1. Field of the Invention
This invention is concerned with trays and containers adaptable for holding food, often containing fats, for cooking in a microwave oven.
2. Description of the Prior Art
It is well known in the art to produce various shaped articles from foamed and unfoamed polystyrene sheet by thermoforming methods. Many such articles are containers used for packaging foods.
Polystyrene containers, however, are melted by hot fats and cannot be used to package fat-containing foods that are to be heated in a microwave oven. Similarly, containers made from poly(p-methylstyrene) are not per se resistant to hot fats when heated in a microwave oven. In general, containers made from any polymer or copolymer with a softening temperature below 190.degree. F. (87.8.degree. C.) are not resistant to hot fats when heated in a microwave oven.
It is the discovery of this invention that containers made from laminates of heat resistant film and foamed or unfoamed sheet of polymers or copolymers with a softening temperature below 190.degree. F. (87.8.degree. C.), in which the heat resistant film is on the interior surface, are resistant to hot fats when heated in a microwave oven.